Powder based balancing layer

ABSTRACT

A method of manufacturing a building panel with a decorative surface layer, a core and a balancing and/or protective layer, wherein the method includes applying a first layer of a first powder based mix, including wood fibers and a thermosetting binder, on a core; applying a liquid substance on the first powder based mix; drying the first powder based mix; turning the core with the dried first powder based mix such that the first powder based mix points downwards; applying a second layer on the upper part of the core; and curing the first and second layers by providing heat and pressure, wherein the first layer forms the balancing and/or protective layer and the second layer forms the decorative surface layer in the building panel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/444,653, filed on Apr. 11, 2012, which claims the benefit of SwedishApplication No. 1150320-8, filed on Apr. 12, 2011, Swedish ApplicationNo. 1151058-3, filed on Nov. 9, 2011, U.S. Provisional Application No.61/474,498, filed on Apr. 12, 2011, and U.S. Provisional Application No.61/557,734, filed on Nov. 9, 2011. The entire contents of each of U.S.application Ser. No. 13/444,653, Swedish Application No. 1150320-8,Swedish Application No. 1151058-3, U.S. Provisional Application No.61/474,498, and U.S. Provisional Application No. 61/557,734 are herebyincorporated herein by reference.

TECHNICAL FIELD

The disclosure generally relates to the field of panels with adecorative surface layer and a balancing and/or protective layer,preferably floor and wall panels. The disclosure relates to productionmethods to produce such panels.

FIELD OF APPLICATION

Embodiments of the present invention are particularly suitable for usein production of floating floors, which are formed of floor panelscomprising a core and a decorative wear resistant solid surface layercomprising fibres, binders and wear resistant particles that have beenapplied on the core as a powder as described in WO 2009/065769. Thefield of application comprises products with other types of decorativelayers such as paper based, laminated panels (DPL), where a balancingand/or a protecting layer is used. The following description oftechnique, problems of known systems and objects and features of theembodiments of the invention will therefore, as a non-restrictiveexample, be aimed above all at this field of application and inparticular at floorings which are similar to traditional floating woodfibre based laminate floorings. The invention does not exclude floorsthat are glued down to a sub floor. Embodiments of the invention canalso be used in building panels such as for example wall panels,ceilings, and furniture components and similar.

BACKGROUND

Wood fibre based direct pressed laminated flooring (DPL) usuallycomprises a core of a 6-12 mm fibre board, a 0.2 mm thick upperdecorative surface layer of laminate and a 0.1-0.2 mm thick lowerbalancing and/or protective layer of laminate, plastic, paper or likematerial.

The surface layer of a laminate floor is characterized in that thedecorative and wear properties are generally obtained with two separatelayers one over the other. The decorative layer is generally a printedpaper and the wear layer is a transparent overlay paper, which comprisessmall aluminium oxide particles.

The printed decorative paper and the overlay are impregnated withmelamine formaldehyde resin and laminated to a wood fibre based coreunder heat and pressure. The balancing layer is used to keep the panelflat after production and when the panel is exposed to variations inmoisture conditions that cause the surface layer to swell and shrink.

Recently new “paper free” Wood Fibre Floor (WFF) types have beendeveloped with solid surfaces comprising a substantially homogenous mixof fibres, binders and wear resistant particles.

The wear resistant particles are preferably aluminium oxide particles,the binders are preferably thermosetting resins such as amino resins andthe fibres are preferably wood based. Other suitable wear resistantmaterials are for example silica or silicon carbide. In mostapplications decorative particles such as for example colour pigmentsare included in the homogenous mix. In general all these materials arepreferably applied in dry form as a mixed powder on a HDF core and curedunder heat and pressure to a 0.1-1.0 mm solid layer.

Several advantages over known technology and especially overconventional laminate floorings can be obtained:

-   -   The wear resistant surface layer, which is a homogenous mix, can        be made much thicker and a wear resistance is achieved, which is        considerably higher.    -   New and very advanced decorative effects can be obtained with        deep embossing and by separate decorative materials, which can        be incorporated into the homogenous surface layer and        coordinated with the embossing.    -   An increased impact resistance can be reached with a homogenous        surface layer, which is thicker and has a higher density.    -   The homogenous surface layer can comprise particles that have a        positive impact on sound and moisture properties.    -   Production costs can be reduced since low cost and even recycled        materials can be used and several production steps can be        eliminated.

Powder technology is very suitable to produce solid decorative surfacelayer, which are much thicker than conventional laminate surface layers.Such solid powder based layers create a much higher tension on the panelwhen they shrink (or swell) during curing and balancing is a problem. Itis therefore difficult to produce a panel with a thick and a highquality surface, which is also well balanced after pressing as well asstable and flat in variable moisture conditions.

Definition of Some Terms

By “surface layer” is meant all types of surface layers, which give thepanel its decorative properties and its wear resistance. By a “WFF mix”is meant a mix of materials comprising fibres, binders, wear resistantparticles and, optionally, a colour substance, which is preferablyapplied as powder on a carrier.

By “WFF floor” is meant a floor panel comprising a solid surface, whichis obtained by a WFF mix that is preferably applied as dry powder on acore, such as for example HDF, and cured under heat and pressure.

Known Technique and Problems Thereof

The new “paper free” WFF floors with a solid surface comprising a WFFmix of fibres, preferably wood fibres, small, hard wear resistantparticles and a binder are produced according to a production methodwhere the WFF mix is applied in powder form on a core. The wood fibresare generally refined, mechanically worked, and of the same type as usedin HDF and particleboard, i.e. treated in a way that the lignin contentis essentially unchanged. They comprise natural resins such as lignin.The wear resistant particles are preferably aluminium oxide particles.The surface layer comprises preferably also colour pigments or otherdecorative materials or chemicals. Processed fibres e.g. bleached woodfibres may also be used. Processed fibres may be semi-transparent, andare preferably transparent in a cured binder.

A preferred binder is melamine or urea formaldehyde resin. Any otherbinder, preferably synthetic thermosetting or thermoplastic resins, maybe used. The WFF layer is generally scattered in dry powder form on awood based core, such as for example HDF.

The backside of the core is covered by a balancing layer, whichcomprises one or several papers impregnated with melamine resin in orderto get a balanced product after pressing. The panel is generallyproduced with a surface that is slightly convex in order to be able tostay flat even in very dry conditions.

The total build up with decorative layer, core and balancing orprotective layer is transferred into a press, where the decorative layerand the balancing or protective layer are cured, under the influence ofheat and pressure.

By a protective layer is meant a layer adapted to protect the backsideof the core.

The curing of a melamine formaldehyde (MF) resin involves shrinkage ofthe MF resin matrix and the balancing layer is needed to balance theshrinkage forces from the decorative layer.

Paper based backer materials can create problems as the paper always hasa dominating fibre direction either in the production direction orperpendicular to the production direction. The shrinkage during curingis always higher in the transverse direction of the fibres as the fibrescan be packed together closer in this direction. The implication of thisbehavior is that the balancing layer has different shrinkage in theproduction direction compared with the transverse direction.

As the backer is used to balance the decorative layer, which may as anexample comprise a powder mix with random fibre direction, theconsequence is that an optimized balancing only can be obtained in onedirection, either along or perpendicular to the production direction. Itis also complicated to adapt the thickness of the paper to differentthicknesses of the surface layer.

However, the paper based balancing layer offer the advantages that thepaper is rather easy to transport together with the core under thescattering units and into a press.

It is known from WO 2009/065769 that the balancing layer can be createdwith a powder layer that is applied on the backside of the core. Thisknown disclosure does not show how a powder layer on a back side of acore should be handled in order to allow a cost efficient production,especially when discontinuous presses are used which require that thecore with its powder based layers can be fed in high speed with clampingdevices into a press.

The above description of various known aspects is the applicants'characterization of such, and is not an admission that any of thedescription is prior art.

OBJECTS AND SUMMARY

An objective of certain embodiments of the invention is to provide abuilding panel, preferably a floor panel with a decorative surface layerand a balancing and/or protective layer which can be produced in a costefficient way.

A first aspect of the invention is a method of manufacturing a buildingpanel with a decorative surface layer, a core and a balancing and/orprotective layer. The method comprises the steps below and preferablyperformed in the listed sequence:

-   -   applying a first layer of a first powder based mix, comprising        wood fibres and a thermosetting binder on a core;    -   applying a liquid substance on the first powder based mix;    -   drying the first powder based mix;    -   turning the core with the dried first powder based mix such that        the first powder based mix points downwards;    -   applying a second layer on the upper part of the core; and    -   curing the first and second layers simultaneously by providing        heat and pressure, wherein the first layer forms the balancing        and/or protective layer and the second layer forms the        decorative surface layer in the building panel.

The method offers the advantages that a powder based balancing orprotective layer can be applied in a cost efficient way by scattering ona core. The powder may be fixed to the core with a liquid substance thatswells, partly dissolves or dissolves the resin, thereby making thepowder tacky and stick together. A drying step removes part of the waterthus leaving the powder glued not only to itself but also to the core.The attachment makes the first layer stable such that the core with thefirst layer can be turned and fed under scattering units and into apress. A paper based balancing or protective layer can be replaced in acost efficient way by a wood fibre based layer with random fibredirection that has similar shrinkage properties as the decorativesurface layer.

The building panel may be a floor panel.

The core may be a HDF or MDF board.

The second layer may comprise a veneer layer. Thereby, the veneer layerforms the decorative surface layer. The second layer may comprise asheet-shaped layer of wood. A curable lacquer may be applied on top ofthe veneer layer.

The second layer may comprise a first paper sheet. In this embodiment,the second layer forming the decorative surface layer is a laminate suchas a DPL (direct pressed laminate) or HPL (high pressure laminate).

The second layer may further comprise a second paper sheet.

The first and/or the second paper sheet may be impregnated with athermosetting resin such as melamine formaldehyde.

The first paper sheet may be arranged such that the fibre direction ofthe first paper sheet is extending in a first direction, and the secondpaper sheet may be arranged such that the fibre direction of the secondpaper sheet is extending in a second direction, said second directionbeing transverse to the first direction.

The second layer may comprise a second powder based mix comprising woodfibres, binders, preferably a thermosetting binder, and wear resistantparticles. Thereby, the second layer can be applied in the same way asthe powder based balance or protective layer by scattering on the core.

The method may comprise the further step of applying a print or a coloursubstance into the second mix.

A second aspect of the invention is a method of manufacturing a buildingpanel with a decorative surface layer, a core and a balancing and/orprotective layer. The method comprises the steps below and is preferablyperformed in the listed sequence:

-   -   applying a first layer of a first powder based mix, comprising        wood fibres and a thermosetting binder on a carrier, preferably        of a thin material with a thickness that does not exceed the        thickness of the decorative surface layer;    -   placing the core material on the first powder based mix;    -   applying a second layer on the upper part of the core; and    -   curing the first and second layers by providing heat and        pressure wherein the first layer forms the balancing and/or        protective layer and the second layer forms the decorative        surface layer of the building panel.

The method offers the advantages that a powder based balancing orprotective layer can be applied in a cost efficient way by scattering ona carrier that keeps the powder based balancing or protective layerconnected to the core during transport to the device that applies thesurface layer and finally when the core is fed into the press.

The building panel may be a floor panel.

The core may be a HDF or MDF board.

The carrier may be a fibre based material.

The second layer may comprise a veneer layer. Thereby, the veneer layerforms the decorative surface layer. A curable lacquer or powder mixlayer may be applied on top of the veneer layer.

The second layer may comprise a first paper sheet. In this embodiment,the second layer forming the decorative layer is a laminate such as aDPL (direct pressed laminate) or HPL (high pressure laminate).

The second layer may further comprise a second paper sheet.

The first and/or the second paper sheet may be impregnated with athermosetting resin such as melamine formaldehyde.

The first paper sheet may be arranged such that the fibre direction ofthe first paper sheet is extending in a first direction, and the secondpaper sheet may be arranged such that the fibre direction of the secondpaper sheet is extending in a second direction, said second directionbeing transverse to the first direction.

The second layer may comprise a second powder based mix comprising woodfibres, binders, preferably a thermosetting binder, and wear resistantparticles. Thereby, the second layer can be applied in the same way asthe powder based balance or protective layer by scattering on a core.

The method may comprise the further step of applying a print or a coloursubstance into the second mix.

A third aspect of the invention is a method of manufacturing a separateand continuous powder based balancing and/or protective layer, which isessentially uncured. The method comprises the steps below and ispreferably performed in the listed sequence:

-   -   applying a powder mix comprising fibres and a thermosetting        binder on a carrier;    -   applying moisture on the powder mix such that the powder mix is        connected together to an essential uncured balancing and/or        protective layer; and    -   releasing the uncured balancing and/or protective layer from the        carrier.

The separate and continuous powder based balancing or protective layermay be used in a method for producing a building panel which methodcomprises the steps below and is preferably performed in the listedsequence:

-   -   placing the uncured balancing and/or protective layer under a        core material;    -   applying a surface layer on the core material; and    -   curing the surface layer and the uncured balancing and/or        protective layer under heat and pressure.

The method offers the advantages that a powder based balancing orprotective layer can be produced as a separate uncured layer that can behandled as a conventional paper based balancing or protective layer. Themoisture, that preferably comprises water, may be sprayed on the powdersuch that the binder, preferably a melamine resin, moisture swells,partly dissolves or dissolve the resin, thereby making the powder tackyand stick together. The fibres in the mix will be connected to eachother when the water dries. The fibres may also be connected by applyingheat, e.g., IR heating, thereby removing the moisture and connecting thefibres in the mix. A powder based uncured balancing or protective layermay be formed as a flexible thin sheet and a core material may be placedover the balancing or protective layer.

The surface layer may comprise a powder based surface layer, at leastone paper sheet or a veneer layer.

A fourth aspect of the invention is a separate and continuous powderbased balancing and/or protective layer, which is essentially uncured.The separate layer comprises powder mix comprising connected fibres andan essentially uncured thermosetting binder.

The powder based balancing or protective layer is preferably producedaccording to the method of the third aspect.

A fifth aspect of the invention is a building panel, comprising a core,preferably a wood-based core such as MDF or HDF board, a decorativesurface layer arranged on a first surface of said core, the decorativesurface layer comprising at least one paper layer, and a balancing layerarranged on a second surface of said core, said second surface beingopposite to said first surface, wherein the balancing layer is formed ofa powder based mix comprising wood fibres and a thermosetting binder.

The building panel is preferably produced according to the first orsecond aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in connection topreferred embodiments and in greater detail with reference to theappended exemplary drawings, wherein,

FIGS. 1a-e illustrate a method to form a balancing and/or protectivelayer.

FIGS. 2a-e illustrate a method to form a balancing and/or protectivelayer.

FIG. 3 illustrates a building panel wherein the decorative layer islaminate.

FIG. 4 illustrates a building panel wherein the decorative layer is aveneer layer.

DETAILED DESCRIPTION OF EMBODIMENTS

The powder intended to be used as a balancing and/or protective layer 3is applied as a first powder mix on a core 2, preferably a MDF or HDFmaterial, preferably by one or several scattering units 11 as shown inFIG. 1a . FIG. 1b shows that the powder is thereafter pre-stabilized bya fluid 7, preferable based on water, which is applied by a stabilizingdevice 9. The first powder layer is thereafter dried. Such drying can beperformed off-line in a controlled environment or in-line by applyingheat 8 with a heating device 10 on the powder mix 3. The heating device10 may comprise infrared light. The water based fluid 7 and thefollowing drying 8, attaches the powder layer 3 to the core 2, to suchan extent that the core 2 with the powder can be turned 180° to bringthe powder based balancing or protective layer 3 downwards, as shown inFIG. 1c , such that it may be transported further along the productionline or be stacked on a pallet for intermediate storage before furtherproduction takes place.

Oversized or undersized fibres from the hammer mill that produces thefibres for the surface layer may be used in the balancing or protectivelayer mix. The fibre size is not as critical as in a powder basedsurface layer and may vary from a fibre length of several mm to lessthan 0.1 mm. The most preferred average fibre length is 0.1-1.0 mm.

A second powder based surface layer mix 1 is thereafter applied on theupper side of the core 2 as showed in FIG. 1d . A digital print 4 may beprinted into the surface layer 1. The surface layer 1 preferably alsocomprises wood fibres, a colour substance, thermosetting binders andaluminium oxide particles.

The wood fibres in both the first and second powder mixes in allembodiments of the invention may be virgin, unrefined, refined and/orprocessed, comprising lignin and without lignin, e.g. α-cellulose fibresor holocellulose. A mixture of refined and unrefined fibres may also beused. It is also contemplated that vegetable fibres as jute, linen,flax, cotton, hemp, bamboo, bagasse and sisal may be used. Also mineralfibres and carbon fibres may be used.

As an alternative to the second powder based surface layer mix, thesecond layer forming the decorative surface layer may comprise at leastone paper sheet 21 adapted to form a laminate, which is shown in FIG. 3.Said at least one paper sheet 21 may be arranged on the upper side ofthe core. Preferably, the second layer comprises a first paper sheet 21and a second paper sheet 22. The first and second paper sheets 21, 22may be arranged such that the fibre direction of the first paper sheet21 is extending in a first direction, and the fibre direction of thesecond paper sheet 22 is extending in a second direction being oppositeto the first direction. By arranging the fibre direction of the sheetstransversely, the second layer has fibre directions in more than onedirection. Thereby, during shrinkage, the second layer obtainsproperties more similar to the balancing or protective layer having arandom fibre direction compared to a surface layer having only onedominating fibre direction.

The first paper sheet 21 may be a printed paper. The second paper sheet22 may be a transparent overlay paper. The second paper sheet 22 mayform a wear layer and may comprise small aluminium oxide particles. Thefirst and second paper sheets 21, 22 may be impregnated with melamineresin such that they can be laminated to the core under heat andpressure simultaneously as curing the balancing and/or protective layer.The second paper sheet 22 may be arranged on top of the first papersheet 21.

Alternatively, the second layer may comprise a veneer layer 23 orsheet-shaped layer of wood arranged on the upper side of the core, whichis shown in FIG. 4. The second layer may further comprise a curablelacquer layer applied on top of the veneer layer or sheet-shaped layerof wood. The curable lacquer layer may be cured simultaneously as curingthe balancing and/or protective layer.

Other décor layers may also be used as a second layer, such as cork,rubber, plastics, especially a thermoplastic décor layer.

The core 2 with the surface layer 1 and the balancing or protectivelayer 3 is thereafter fed into a press where the layers are cured underheat and pressure. The balancing layer may be optimized in thickness andmaterial composition in order to create a perfect balancing of thesurface layer. The fibre orientation in the layers may be essentiallythe same.

Recycled fibres from the machining of the panels, for example when amechanical locking system is formed, may be used in the balancing orprotective layer mix.

The balancing or protective layer 3 may preferably comprise a homogenouspowder mixture comprising about 50 weight % recycled MDF fibres with amoisture content of preferably 3-8% and about 50 weight % MelamineFormaldehyde (MF) resin (Prefere 4865, Dynea). The MF resin amount canvary between 30-70 w-%, preferably 40-65 w-% and most preferably 45-60w-%. The fibre content may vary from 30-70%, most preferably between40-55%.

If needed the powder formulation can be modified such that thermosettingparticles, pigments, hard particles, release agents, wetting agents andsimilar materials are included into the mix. The thermosetting plasticparticles may be mixed at random into the powder or applied as aseparate thin layer and may be used to provide a sealing againstmoisture penetration into the core.

The core of an HDF board preferably has a moisture content of 0-8%.

The scattering unit 11 may have capacity of scattering of 100-1000 g/m²with a tolerance of +/−5% as measured using a calibration cup with anarea of 100×100 mm cross- and length wise the board. The amount ofstabilization fluid may vary from 0 up to 200 g/m².

The scattering unit 11 may comprise a needle belt and a scatteringroller 12. The scattering roller is provided with needles in the rangeof about 30-120, preferably about 50-100, and most preferably about70-90 needles per cm². The needle length is about 0.5-2.5 mm, preferablyabout 1-2 mm and most preferably about 1.5 mm. Several scattering units11 may be used to even out differences in the applied powder mixture.

Furthermore, the scattering unit may be provided with a needle belt withneedles with a preferred length of about 15-20 mm, a preferred frequencyin the range of about 500-1000 rpm preferably about 1000 rpm, and astroke length of about +/−3 mm.

The stabilizing device 9 and the heating device 10 may be used tostabilize the surface layer 1 and/or the balancing or protective layer3.

The stabilization device 9 may stabilize the powder using steam, nozzlespray coating or ultra-sonic spray coating.

Stabilization fluid may comprise solvents such as non-polar solvents,polar aprotic solvents and polar protic solvents or mixtures thereof.Preferred solvents are polar protic solvents such as isopropanol,ethanol and water. Most preferred is water.

The stabilization fluid can further comprise additives such as wettingagents, defoamers, release agents, anti-slip agents and catalysts.

FIGS. 2a-2e show how a powder based balancing or protective layer can beapplied by applying the powder based balancing or protective layer as afirst mix 3 on a carrier 5. The core is applied on the mix (FIG. 2c )and a powder based surface layer 1 is applied on the core 2.Alternatively, a surface layer of at least one paper sheet 21 or veneerlayer 23 is applied to the core for forming a decorative surface layer,as described above with reference to FIGS. 3 and 4. Stabilizing and/orheating of the balancing and/or surface layers may be made as describedabove. The core and layers are fed into a press and cured under heat andpressure to a building panel as shown in FIG. 2 e.

The carrier may be a paper with a weight of for example 100-200 gr. Itmay also be a non-woven fibre based material or a foil.

Powder may also be applied on a carrier that preferably is a conveyorbelt 11 and stabilized with fluid and dried such that it can be releasedfrom the conveyor 11 and handled as a separate sheet without the carrier5 as shown in FIG. 2b . Such a separate and continuous sheet or layer isessentially uncured. The sheet or layer may be flexible such that it maybe bent. The powder may comprise fibres, preferably wood fibres, and athermosetting binder.

EXAMPLES

In example 1 below the powder formulation for the balancing layer usedcomprising 50 weight-% recycled MDF fibre (Välinge Innovation Sweden),50 weight-% Melamine Formaldehyde resin (Prefere 4865, Dynea).

Example 1: Powder Based Product Obtained Through Heat Compression ofProduct Produced with Powder Based Balancing Layer and a Treated Powderas Decorative Layer

A balancing layer was formed by scattering 500 g/m² of powder on a 9.7mm HDF core. 40 g/m² of stabilization fluid with 5 w-% wetting agent, 6w-% release agent and 3 w-% catalyst was applied by spraying on thepowder based balancing layer mix

The powder and the stabilization fluid were applied at a line speed of2.7 m/min. The powder based balancing layer was dried at the same linespeed with IR with an effect of 19 kW.

The resulting intermediate product with a stabilized powder basedbalancing layer was turned 180° and stacked on a pallet before use inthe next operation where a decorative surface layer of 500 gr/m² wasapplied in powder form on the core.

The core with the surface and balancing layers was pressed in a presswith a pressure of 40 kg/cm², during 25 seconds. The upper press tableapplied a heat of 170 degrees C. on the surface layer and the lowerpress table applied a heat of 175 degrees C. on balancing layer.

A panel with a small pre tension backwards and a slightly convex surfacewas obtained.

In example 2 below the powder formulation for the balancing layer usedcomprising 42 weight-% recycled MDF fibre (Välinge Innovation Sweden),58 weight-% Melamine Formaldehyde resin (Prefere 4865, Dynea).

Example 2: Powder Based Product Obtained Through Heat Compression ofProduct Produced with Powder Based Balancing Layer and a Treated Powderas Decorative Layer

A balancing layer was formed by scattering 320 g/m² of powder on a 9.7mm HDF core.

40 g/m² of stabilization fluid with 1 wt-% wetting agent, 6 wt-%rerelease agent and 1 wt-% catalyst was applied by spraying on thepowder based balancing layer mix

The powder and the stabilization fluid were applied at a line speed of2.0 m/min. The powder based balancing layer was dried at the same linespeed with IR with an effect of 19 kW.

The resulting intermediate product with a stabilized powder basedbalancing layer was turned 180° and feed into the next operation where adecorative surface layer of 550 gr/m² was applied in powder form on thecore.

The core with the surface and balancing layers was pressed in a presswith a pressure of 40 kg/cm², during 37 seconds. The upper press tableapplied a heat of 184° C. on the surface layer and the lower press tableapplied a heat of 175° C. on balancing layer.

A panel with a small pre tension backwards and a slightly convex surfacewas obtained.

It is contemplated that there are numerous modifications of theembodiments described herein, which are still within the scope of theinvention as defined by the appended claims.

For example, it is contemplated that the balancing layer may be providedwith an orientation in some embodiments. The wood fibres based thebalancing layer generally has a random fibre direction. However, inorder to form a balancing layer having similar properties as thedecorative surface layer, an orientation may be formed in the balancinglayer. Such orientation may be provided with by means of scattering thepowder in a specific pattern, by a pattern in the press plate, or bymeans of a rake forming a pattern.

The steps of the method claims do not necessarily have to be performedin the above described order. It is for example contemplated that thesecond layer may be applied before the first layer, and that the core isturned after the second layer has been applied. Thereafter the firstlayer is applied, liquid is applied, the first powder based mix is driedand the core is turned with the dried first powder based mix such thatthe first powder based mix points downwards.

The invention claimed is:
 1. A method of manufacturing a building panelwith a decorative surface layer, a core and a balancing and/orprotective layer, wherein the method comprises the steps: applying afirst layer of a first powder based mix, comprising wood fibres and athermosetting binder, on a core; applying a liquid substance on thefirst powder based mix; drying the first powder based mix; turning thecore with the dried first powder based mix such that the first powderbased mix points downwards and an upper part of the core faces upwards;applying a second layer on the upper part of the core; and curing thefirst and second layers by providing heat and pressure, wherein thefirst layer forms the balancing and/or protective layer and the secondlayer forms the decorative surface layer in the building panel.
 2. Themethod as claimed in claim 1, wherein the building panel is a floorpanel.
 3. The method as claimed in claim 1, wherein the core is a HDF orMDF board.
 4. The method as claimed in claim 1, wherein the step ofapplying said second layer comprises applying a veneer layer.
 5. Themethod as claimed in claim 1, wherein the step of applying said secondlayer comprises applying a first paper sheet.
 6. The method as claimedin claim 5, wherein the step of applying said second layer furthercomprising applying a second paper sheet.
 7. The method as claimed inclaim 6, wherein the step of applying said first and second paper sheetscomprises arranging said first paper sheet such that the fibre directionof the first paper sheet is extending in a first direction, andarranging said second paper sheet such that the fibre direction of thesecond paper sheet is extending in a second direction, said seconddirection being transverse to the first direction.
 8. The method asclaimed in claim 1, wherein the step of applying the second layercomprises applying a second powder based mix comprising wood fibres,binders, and wear resistant particles.
 9. The method as claimed in claim8, wherein the method comprises the further step of applying a print ora colour substance into the second mix.
 10. A method of manufacturing abuilding panel with a decorative surface layer, a core and a balancingand/or protective layer, wherein the method comprises the steps of:applying a first layer of a first powder based mix, comprising woodfibres and a thermosetting binder, on a carrier; applying a liquidsubstance on the first powder based mix; placing a lower surface of thecore on the first powder based mix after the liquid substance has beenapplied on the first powder based mix; applying a second layer on anupper surface of the core; and curing the first and second layers byproviding heat and pressure, wherein the first layer forms the balancingand/or protective layer and the second layer forms the decorativesurface layer of the building panel.
 11. The method as claimed in claim10, wherein the building panel is a floor panel.
 12. The method asclaimed in claim 10, wherein the core is a HDF or MDF board.
 13. Themethod as claimed in claim 10, wherein the carrier is a fibre basedmaterial.
 14. The method as claimed in claim 10, wherein the step ofapplying said second layer comprises applying a veneer layer.
 15. Themethod as claimed in claim 10, wherein the step of applying said secondlayer comprises applying a first paper sheet.
 16. The method as claimedin claim 15, wherein the step of applying said second layer furthercomprising applying a second paper sheet.
 17. The method as claimed inclaim 16, wherein the step of applying said first and second paper sheetcomprises arranging said first paper sheet such that the fibre directionof the first paper sheet is extending in a first direction, andarranging said second paper sheet such that the fibre direction of thesecond paper sheet is extending in a second direction, said seconddirection being transverse to the first direction.
 18. The method asclaimed in claim 10, wherein the step of applying said second layercomprises applying a second powder based mix comprising wood fibres,binders, and wear resistant particles.
 19. A method of manufacturing aseparate and continuous powder based balancing and/or protective layer,which is essentially uncured, wherein the method comprises the steps of:applying a powder mix, comprising fibres and a thermosetting binder, ona carrier; applying moisture on the powder mix such that the powder mixis connected together to form an uncured balancing and/or protectivelayer; and releasing the uncured balancing and/or protective layer fromthe carrier.
 20. The method as claimed in claim 19, wherein the fibresare wood fibres and the binder a melamine resin.
 21. The method asclaimed in claim 10, wherein the carrier is of a thin material with athickness that does not exceed the thickness of the decorative surfacelayer.
 22. The method as claimed in claim 1, wherein the step ofapplying the first layer of the first powder based mix is done byscattering.
 23. The method as claimed in claim 1, wherein the step ofdrying the first powder based mix comprises applying heat, the heatbeing applied before the step of turning the core.
 24. The method asclaimed in claim 1, wherein the wood fibres of the first powder mixturepossesses a moisture content of between 3-8 weight-%.
 25. The method asclaimed in claim 1, wherein a stabilization device applies the liquidsubstance on the first powder based mix.
 26. The method as claimed inclaim 25, wherein the stabilization device uses at least one of steam,nozzle spray coating, and ultrasonic coating to apply the liquidsubstance on the first powder mixture.
 27. The method as claimed inclaim 1, wherein the liquid substance further comprises an additive, theadditive comprising at least one of a wetting agent, a release agent, adefoamer, an anti-slip agent, and a catalyst.
 28. A method ofmanufacturing a building panel comprising the steps, performed in order,of: applying a first layer of a first powder based mix comprising woodfibres and a thermosetting binder on a first surface of a core, the corepossessing a second surface positioned opposite the first surface of thecore; applying a liquid substance on the first powder based mix; dryingthe first powder based mix; turning the core with the dried first powderbased mix such that the first surface with the first powder based mixpoints downwards and the second surface of the core faces upwards;applying a second layer on the second surface of the core; and curingthe first and second layers by providing heat and pressure to form thebuilding panel, wherein the first layer forms a balancing and/orprotective layer connected to the first surface of the core and thesecond layer forms a decorative surface layer connected to the secondsurface of the core.